program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  k1, n1, n, i, k: integer;
  c: real;
begin
  readln (n);
  readln (k);
  n1:= 1;
  k1:= 1;
  for i:=1 to n do
  begin
    n1:= n1*i;
  end;
  for i:=1 to n do
  begin
    k1:= k1*i;
  end;
  c:= n1 div (k1*(n-k));
  writeln (c);
  readln;
end.
